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  <meta charset="UTF-8">
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  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
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<body>
  <script>
    let arr = [1,2,3,4,5]
    function handleData(array,item) {
      let sum =0
      for(let i=0;i<array.length;i++){
        sum += array[i]
    }
    if(item === false){
     return sum / array.length
    }else{
      return sum
    }    
      }
    console.log( handleData(arr, false));
    console.log( handleData(arr, true));
    console.log( handleData(arr));


  </script>
</body>
</html>